1. Field of the Invention
The present invention relates to a method for surface treatment of a gold-plated body, a surface-treated product, a method for the manufacture of a gold-plated body, a gold-plated body, and an immobilization method which make it possible to immobilize a large number of sulfur-containing molecules.
2. Description of Prior Art
A technology for immobilizing sulfur-containing molecules having S—H groups, S—S groups, and the like on the surface of gold (Au) (bonding of S—H groups and gold is described in J. Am. Chem. Soc., No. 111, p. 321-, 1989, by C. D. Bain et al., and in Anal. Chem. No. 70, p. 2396-, 1998, by J. J. Gooding et al.) has been known in a variety of fields such as immobilization of probes in gene detection (target gene probe), immobilization of self-assembled monolayers (SAM) as resists (photosensitive agents), and the like.
Gold-plated bodies prepared by plating gold by a usual plating method on the surface of a substrate such as alloy substrate have been used as gold serving as immobilization substrates for such sulfur-containing molecules.
However, a problem associated with such gold-plated bodies was that only a small amount of sulfur-containing molecules could be immobilized on the surface thereof. This was apparently because the orientation of gold crystal structure on the surface of gold plated body was not constant which resulted in a decreased amount of bonds (coordination bonds) between gold and S—H groups or S—S groups contained in the sulfur-containing molecules.
Appropriately changing gold plating conditions such as temperature in the process of forming a gold-plated body was considered as a means for obtaining a constant orientation of surface structure of the gold-plated body and immobilizing a large amount of sulfur-containing molecules on the gold-plated body. However, changing of such conditions was in reality difficult.